The energy industry is getting active in a second potentially oil-rich shale formation in Louisiana, this one stretching across the northern part of the state, Department of Natural Resources Secretary Scott Angelle said Wednesday.

Angelle said in a news release that he is “bullish” on the future of energy production and its role in providing jobs and economic strength in Louisiana.

Houston-based Southwestern Energy Co. apparently feels the same way. The company recently announced it has invested $150 million in mineral leases for 460,000 acres in the Lower Smackover, also known as the “Brown Dense” formation. The name comes from the rock in the formation: dark-colored lime and mud stone.

Southwestern Energy is drilling its first Brown Dense well in Arkansas and has applied for a permit to drill one in Claiborne Parish near the Arkansas border. Southwestern says it will begin drilling that well by the end of the year.

Natural Resources Department spokeswoman Anna Dearmon said the agency doesn’t know of any reserve estimates for the amount of oil in the Lower Smackover.

The formation joins the Tuscaloosa Marine Shale that stretches across Louisiana’s midsection as the second shale formation believed to have potential for oil production. A third formation — the Haynesville Shale — is a major natural gas producer in northwest Louisiana.

The Lower Smackover, or Brown Dense formation, is 300 to 500 feet thick and lies some 8,000 to 10,000 feet below ground. It is at the base of the Smackover formation — which has long been a source for traditionally produced oil and natural gas in north Louisiana.

Don Briggs, president of the Louisiana Oil and Gas Association, said the Brown Dense is thought to stretch from east Texas through northern Louisiana and southern Arkansas, and possibly to Mississippi.

Although there’s some leasing and interest in the formation, there’s very little drilling activity so far, Briggs said.

Oklahoma City-based Devon Energy, which has leased 250,000 acres in the Tuscaloosa Marine Shale, has announced it has 40,000 acres under lease in the Brown Dense. Devon has a permit for a well in Morehouse Parish.

“The technology of hydraulic fracturing and being able to drill laterally is the game changer for the energy industry,” Briggs said. “That changes everything.”

For example, the industry had long known about the enormous natural gas reserves in the Haynesville Shale, Briggs said.

But a well drilled vertically into the formation might encounter a productive area of 200 feet at most, he said. By drilling horizontally, the productive area is expanded to 4,000 feet, and that is a huge difference.

In hydraulic fracturing, chemicals, water and sand are injected into the ground under enormous pressure, cracking the rock and propping it open. The oil or natural gas escapes through those openings.

Fracking technology is the reason that energy companies have targeted the Tuscaloosa Marine Shale, which crosses Louisiana’s mid-section and is thought to contain 7 billion barrels of oil. More than 1 million acres in the Louisiana portion of the shale are under lease.

According to the Department of Natural Resources, a half-dozen wells in the Marine Shale are in the permitting process or already being drilled.

“The development of the Haynesville Shale natural gas play, the top-producing natural gas play in the nation, has helped give them that confidence,” Angelle said of the interest in the Tuscaloosa Marine and Lower Smackover shales.

Wilma Subra, an environmental chemist and a State Review of Oil and Natural Gas Environmental Regulations board member, said one of the issues with fracking is that the process uses an estimated 5 million to 8 million gallons of water per well.

At first, energy companies in the Haynesville Shale were using ground water, but conservation advocates pushed the companies to switch to surface water — water from rivers and lakes, Subra said. But now surface water resources are falling, and that’s a real concern for people in the area, especially with the current drought.

According to the state Office of Conservation, companies drilling in the Lower Smackover, or Brown Dense, plan to use surface water and recycled water for their overall project needs.

However, Subra said the drought in north Louisiana and fracking operations in the Haynesville Shale are putting pressure on even the supplies of surface water.

Shreveport may have to begin drawing water from the Red River, she said. While the Office of Conservation regulates ground water, the state doesn’t have an agency that can say who can and cannot use surface water nor is there an agency that’s studying who should have first claim on that water, she said.